Some classes of threaded fasteners are intended to be set by tool engagement at only one end. An example is the well known Hi-Lok fastener sold by Hi-Shear Corporation of Torrance, Calif., exemplified by U.S. Pat. No. 2,940,495 to Wing.
Such fasteners have a non-circular, usually hexagonal array of driving surfaces on their internally threaded collars, and a non-circular, usually hexagonal array of wrench engaging surfaces in the end of their externally threaded pin. A wrench to set this fastener includes a power driven socket to engage the collar, and a non-rotating key to engage in the pin recess. When the collar is turned and the pin is restrained, the collar is tightened down onto the pin and the fastener is set An example of such a wrench is shown in U.S. Pat. No. 2,882,773 to Wing, which is incorporated herein in its entirety for its showing of the general properties of such a tool.
Pervasive problems with this type of tool are the tendency of the key to twist or otherwise deform, and the fact that changing the key after damage, or changing it to a different size, is a relatively slow procedure.
It is an object of this invention to provide a key for such a wrench which has an improved resistance to twisting deformation, or bending.
It is another object of this invention to provide a tool whose key can quickly be changed to a different size, or to replace a damaged key.